Aion Electronics Fractal Overdrive Quick Start Manual - Page 2
Browse online or download pdf Quick Start Manual for Music Pedal Aion Electronics Fractal Overdrive. Aion Electronics Fractal Overdrive 7 pages.
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Parts
Resistors
R1
1k
R2
1M
R3
10k
R4
680k
R5
270k
R6
22k
R7
22k
R8
22k
R9
470R
R10
3k3
R11
2k2
R12
2k2
R13
22k
R14
22k
R15
22k
R16
22k
R17
10k
R18
10k
R19
10k
R20
1M
R21
1k
R22
1k
R23
10k
R24
1k
Build Notes
The stock clipping diode setup is nonstandard—it uses two 1N914s, each in series with a 1k resistor (R21
1
and R22). This will give slightly softer clipping than just the diodes. D5–D8 are there so you can experiment
with alternate diode arrangements. This circuit is sensitive to high clipping thresholds, so you probably won't
want to go much higher than 1.2V (two 1N914s in series)—LEDs are not recommended. For the same
reasons, I would not recommend using a center-off switch for the diode selector.
In the original unit, R27 was a 3k3 resistor and R28 was actually a 5.1v zener diode. This is because the
2
whole line of pedals shared the same schematic block for the power supply, and it was developed for the
phaser, flanger and delay which needed a fixed bias point that was independent of the battery's drifting
voltage. However, for an overdrive that needs higher headroom, this is a very bad idea because it means
that the reference voltage is unbalanced and half of the waveform can hit its rail more quickly than the other
half. Accordingly, this circuit has been updated to use a more standard voltage divider. There's a stripe on the
silkscreen of R28 indicating the original diode's orientation, though, if you want it to be 100% accurate.
The original uses 100uF here, which seems like overkill to me. 47uF should be more than adequate.
3
This is not present in the original, but it's in nearly every other feedback diode clipping circuit (such as the
4
Tubescreamer). I'd recommend including it since its function is to tame harshness as the gain is increased.
PEARL OD-05 OVERDRIVE / FRACTAL OVERDRIVE
1
1
Resistors (cont.)
R25
10k
R26
10k
R27
10k
2
R28
10k
2
RPD
1M to 2M2
LEDR
4k7
Capacitors
C1
33n
C2
1uF
film
C3
10uF
electro
C4
47uF
3
electro
C5
1uF
film
C6
4n7
C7
68n
C8
100n
C9
470pF
MLCC
C10
100n
C11
220n
C12
15n
C13
1uF
film
C14
100uF
electro
C15
47uF
electro
CX1
47pF
4
MLCC
Semiconductors
Q1–Q4
2N5088
IC1–IC2
JRC4558D
D1
1N4002
D3, D4
1N914
D5–8
1N914
LED
5mm LED
Potentiometers
Drive
100kB
Volume
10kB
EQ Gain
10kB
5
Frequency
100kC
dual
Other
Clip
SPDT
1
1
1
6
2